Introduction

It is possible to control pH digitally using electronic valves and various solutions(acidic, basic and distilled water). The schematic diagram is attached below. The valves work in such a way that when a voltage is past through the gate, the valves which is normally closed, will open and allow the solution to flow through it. To lower the pH of the solution(make it more acidic), voltage can be past through the valves containing the acidic solution to allow it to flow through and mix with the solution making it more acidic. Likewise for increasing the pH, basic solution can be added. The purpose of distilled water is to dilute the solution. For example if i wan to increase the pH of the solution from 5 to 6, i can just add water instead of a base to increase the pH. This is to prevent the formation of minerals. The drain is used to keep the volume of the solution constant to make the measurement simple. This can be done by draining the same volume of solution before adding the acid or base.

The choice of the acid is Hydrochloric Acid and base is Sodium Hydroxide. The reason is because when they combine, they produce Sodium Chloride which is salt which is not harmful to the plant. The range of pH that we are interested is between the range of 3 to 11. So we will have to use diluted Hydrochloric Acid with pH of 4 and diluted Sodium Hydroxide with pH of 11.

*The flow rate of the valves should be noted to compute the time taken for the required amount of solution to flow out. The exact calculation will be illustrated in the following section.